As a method of detecting whether or not a measuring target substance (for example, water) is included in an object, a water measurement method of measuring water of the measuring target for each pixel based on two-dimensional image data of each pixel acquired by imaging the measuring target using measuring light which is within an absorption wavelength range of water and two-dimensional image data of each pixel acquired by imaging the measuring target using reference light which is not within the absorption wavelength range of water has been known (for example, see PTL 1).
A road surface monitoring system which includes a mechanism which swings an output direction of a laser beam up, down, left, and right and remotely monitors a road-surface state using the swing mechanism of the laser beam by performing surface irradiation on a road surface while varying an incidence angle in a range of α° in the up and down direction and in a range of β° in the left and right direction and receiving reflection light of the laser beam generated through the surface irradiation has been known (for example, see PTL 2).